How to Create and Use a Black Hole Computer Drive?

I have been working on a futuristic story where information can be stored and used with a black hole. This is a highly advanced human society that has accomplished interstellar space travel via both worm holes and warp drive.

My question is this:

How might a race utilize a Black Hole for information storage?

Note that I want both the how to store the information and how to extract the information in a fast (at least 50 mbps) fashion. You can use any sufficiently advanced technology as long as you can provide a brief explanation of what it does and how (in general, of course) it accomplishes its task.

• For anyone interested, check Wikipedia. That's a slight issue. – HDE 226868 Apr 8 '15 at 15:59
• Um, you are so far into the realm of madness that lies on the edge of our knowledge of the physical universe that terms like 50mbps are kinda meaningless. – Emmett R. Apr 8 '15 at 16:10
• Can you explain why you want to use a black hole as a data drive? – Dan Smolinske Apr 8 '15 at 16:19
• A minuscule black hole hasn't been detected and it is said that these black hole instantly vanished leaving little to no trail. Black hole are probably one of the most intriguing subject in physic but that doesn't mean everyone can abuse it. – user6760 Apr 8 '15 at 16:33
• @DanSmolinske A lasting monument to our technological prowess. It has to survive for the duration of that black holes existence. – JDSweetBeat Apr 8 '15 at 16:58

Assuming the holographic principle holds true, and that's a huge assumption, then you could use a black hole itself as a nearly complete, absolutely maximal, horrifically fragile, computational device. However, you wouldn't be storing information inside the black hole, but on its surface.

In contradiction to what 2012rcampion states, there is some speculation that information can be extracted from perturbations in the event horizon, as these perturbations determine the type and properties of emitted Hawking radiation. Computations could be performed by basically dropping things into the black hole and watching what pops back out.

Since the ability to retrieve information from a black hole depends on Hawking radiation, you aren't likely to have a good storage solution for more than a few instants. It would be more of a particularly brief delay-line memory than any long-term storage.

Seth Loyd, in his paper Ultimate Physical Limits to Computation, theorizes that such a computer could possibly exist, but would be very hard to distinguish from a thermonuclear explosion. To summarize how the paper describes black hole computation, your hardware would take a carefully designed ball of matter that represents the program to be run, compress it into a singularity, and examine the resulting burst of radiation and plasma to get the result of the computation. Good luck trying to play Dwarf Fortress on that. You will probably get firsthand experience with Losing is Fun.

On the other hand, current quantum computers are actually edging quite close to the theoretical limits mentioned in Seth's paper, without requiring the total annihilation of matter. This might be a better route, but nowhere near as cool.

• I just had a wonderful thought. This would mean that a computer crash would likely have a body-count. And a blast radius. And a successful computation could render the region uninhabitable for generations... – Emmett R. Apr 8 '15 at 17:13
• what comes out is random. You have to perform a measurment that includes all of the Hawking radiation to ever come off it as it evaporated, and analyse the way it is entangled. But you can't probe the entangement; at best you can confirm that you knew. So it's not really something you can read out. – JDługosz Apr 9 '15 at 6:45
• @JDługosz Well, that's why you'd use a sufficiently small mass that the evaporation time would be on the order of nanoseconds or less. Also, would being able to confirm prior entanglement being broken or maintained be enough to construct a universal computation system? – Emmett R. Apr 9 '15 at 15:57
• No, you cannot confirm prior entanglement being broken or maintained. You onlynget one shot to measure an observable that is part of an entangled state. Say I have two particles that may have entangled spin. I measue one as Up and the other as Down. Does that mean they were constrained via entanglement to be opposites, or was it just a 50% chance that they were opposite without constraints? – JDługosz Apr 10 '15 at 1:28

You can put light pulses into orbit around a black hole, so at the very least you can use it as a data storage device. If the energy density is high enough (gamma rays or higher) then you can get photon-photon interactions that can be used as gates in a computation: https://en.wikipedia.org/wiki/Two-photon_physics. By timing & spacing the pulses, you can set up arbitrary computations.

See Egan's story "The Planck Dive": http://gregegan.customer.netspace.net.au/PLANCK/Complete/Planck.html

If you want "cool", read through this overview of Seth's conclusions.

• A cold degenerate star could conceivably be used as a giant data storage device, by carefully perturbing it to various excited states, in the same manner as an atom or quantum well used for these purposes. Such a star would have to be artificially constructed, as no natural degenerate stars will cool to this temperature for an extremely long time. It is also possible that nucleons on the surface of neutron stars could form complex "molecules" which some have suggested might be used for computing purposes, creating a type of computronium based on femtotechnology which would be faster and denser than computronium based on nanotechnology.

• It may be possible to use a black hole as a data storage and/or computing device, if a practical mechanism for extraction of contained information can be found. Such extraction may in principle be possible (Stephen Hawking's proposed resolution to the black hole information paradox). This would achieve storage density exactly equal to the Bekenstein Bound. Professor Seth Lloyd calculated the computational abilities of an "ultimate laptop" formed by compressing a kilogram of matter into a black hole of radius $1.485 \cdot 10^{−27}\;\text{m}$, concluding that it would only last about $10^{−19}\;\text{s}$ before evaporating due to Hawking radiation, but that during this brief time it could compute at a rate of about $5 \cdot 10^{50}$ operations per second, ultimately performing about $10^{32}$ operations on $10^{16}$ bits ($\approx 1\;\text{PB}$). Lloyd notes that "Interestingly, although this hypothetical computation is performed at ultra-high densities and speeds, the total number of bits available to be processed is not far from the number available to current computers operating in more familiar surroundings."[4]

This is the source of black-hole as computer. But, the cold star might be a cooler idea.

Now what would an advanced civilization need with such a computer? They would already have computronium based on nanotechnology and matrioshka brains. Maybe it's to address the last question as in Asimov's story.

For stories that I remember, Alastair Reynolds Revelation Space series ends with a neutron star computer that, among other things, stores an entire civilization in virtual reality.

I can't remember exactly, but a much older story used a black hole by using time travel to create a paradox with its becoming a black hole.

Of course, you postulate wormholes for travel, so why bother? Just use a closed time-like curve to force the correct answer output by being the only consistent state. Or use wormholes to feed information in to a computer located far away, and another to read the result "now" in our frame even though the computation takes enormous lengths of time at the computer.

(Lightspeed isn't like any familiar speed limit. FTL is time travel. If you connect two arbitrary events in 4D spacetime, you are hopping around time as well as space.)

If you want to use black holes in computing, an interesting idea is to use one as a heat sink, e.g. in a reverse matrioshka brain (it's cold in the center).

Computronium in layered shells operating off the waste heat of the next layer: but put the black hole at the center to serve as a heat sink and more specifically as a bit-bucket to allow information erasure and therefore fast directed computation. These nodes would themselves orbit a hot star for energy input.

Now here's a thought: a Dyson sphere is normally thought to have a thermal signature. But a swarm of black-hole cored computing units would eat up the input and not have any heat flow out. Heat flows to the core and vanishes. So it would appear invisible, not as a black body.

Ok. So here's the thing - you couldn't store information in the black hole, for the reasons mentioned in other answers. But we can measure properties of a black hole, and manipulate those as information storage.

This assumes a technology that, through some completely unknown mechanism, directly manipulates the structure of space time (in other words it can generate warped space directly, instead of creating gravity which then warps space).

Using this tech, you can manipulate the rotation of the black hole in all three dimensions. The entire "hard drive" of the black hole will be encoded into numerical format, and then "written" by modifying the rotation to match the encoded values, using a combination of rotation speeds and inclination.

The entire drive can now be read instantly by precisely measuring the rotation to extremely high digits of precision, which gives infinite read speed among any number of users. Writing is more difficult - you will need to re-encode the entire thing each time, so only one user can place more information at any one time. Speed of write depends on how fast you can change the black hole's rotations.

In order to act as a monument, a Rosetta Stone should be placed in orbit with the decoding structure. Please keep in mind that any write operation will also involve changing the orbit of the Rosetta Stone object.

The black hole will need to be extremely isolated (in between galaxies?) to minimize the impact of other objects, in the long term, on its exact rotations. It probably also needs a protective shell to prevent random intergalactic hydrogen from breaking things.

• The angular momentum is quantized, not an arbitrary precision real number. It will not stay as set, though, even if you sequester it. – JDługosz Apr 9 '15 at 6:41

Instead of manipulating the black hole itself, it might be possible to simply use it to minituraize existing tech. When something goes into a black hole, it is compressed to a singularity, meaning you can get an almost infinite amount of information into an almost infinitely small space. So, you just need to create a hard drive that can store data whilst compressed to a singularity, and find a way of getting it out of the black hole - if your advanced race has mastered creating wormholes, they can probably manipulate the fabric of space-time to temporarily expand the black hole, get the data out and then restore the black hole. If an intergalactic version of Google had this tech, instead of building entire galaxies of servers, they can store said servers in the black hole.

Alternatively, you might be able to create a device that could emit hawking radiation, and put that inside the black hole - it would communicate by emitting radiation. You could 'write' to it by sending things into the black hole - perhaps waste fired in a very specific pattern.

I have a made a few assumptions on the physics of black holes here due to gaps in my knowledge, and basically ignored the problem of collapsing wave functions.

To summarize HDE's point: quantum mechanics tells us that information that falls into a black hole can't just disappear; but relativity tells us that it is impossible for any information to leave a black hole.

Essentially, a black hole is a higly advanced bit bucket.

Let's ignore that fact and look at how much information you could store. Thermodyanmics tells us that the amount of information a black hole can store is at most equal to:

\begin{align} H &= \frac{\pi c^3 r_s^2}{G\hbar} = 1.7\cdot 10^{76}~\text{bits}\times\left(\frac{r_s}{\text{km}}\right)^2 \\ &= \frac{4\pi G M^2}{\hbar c} = 1.5\cdot 10^{77}~\text{bits}\times\left(\frac{M}{M_\odot}\right)^2 \end{align}

Note that this is the maximum amount of information you can store in any volume; that is, gather more information together and it will collapse into a black hole under the gravity of it's own energy. Note also that it's proportional to $R^2$, which means that information density decreases as the amount increases. The maximum "write speed" will be limited by the Eddington luminosity, and the maximum read speed is zero, as before mentioned.

If you're not too worried about the details of the physics, the physics / math as @2012rcampion stated shows that the maximum amount of information that can be stored by a given bit of matter is proportional to the surface area of a black hole that the mass could form (not the volume).

So a Black hole drive would be the ultimate in miniaturization of information technology.

Unfortunately for us, no one has a clue how to read & write to such a device.

A kind of related idea is to use black holes or wormholes to create "basement universes"; small enclosed areas of space time where you could perform massive calculations, extract the answer via the wormhole mouth and pinch off the end to contain the waste heat of the computation engine outside of our universe.

The Orions Arm website describes one such use here: http://www.orionsarm.com/eg-article/48507a11adbd7